There are a number of different types of windows and doors that are currently available. These windows include casement windows, transom windows, single hung window, double hung windows, sliding windows, etc. Double hung windows are windows that have a pair of window sashes that may be raised and lowered. Each sash resides in a pair of tracks or recesses that are typically at each side edge of the window. This permits the lower sash to be raised and the upper sash to be lowered. Traditionally, most windows were made of wood. more recently, the windows including the window sashes have been made of extruded metal or plastic.
Double hung windows originated years ago before the days of air conditioning as a means for cooling a room during the warmer weather. The concept of a double hung window takes advantage of the fact that warm air rises and cooler air is lower in a room. Thus in a room with a double hung window the warm air exits from the opening formed by the lowering of the upper sash and the cooler outside air enters the room through the opening formed by the raised lower sash. In many older buildings the double hung windows may be relatively high and extend from nearly the floor to the ceiling in many rooms. More recently in many buildings, the original concept of the double hung window has been abandoned. Now, most people only open the lower sash to let air either into or out of a room. One reason for this is that many owners of buildings with double hung windows have installed storm windows over the outside of the double hung windows. The storm windows are very useful in reducing the influx of cold air during the cooler months. However, because the annual installation of storm windows has become such a chore, most people have installed the storm windows that store the panes of glass adjacent the upper sash of the storm window. Even in heavily insulated double hung windows that are sold today where there is no need for storm windows typically only the lower sash is raised.
Single hung windows are similar in design to double hung windows except that there is only one sash that may be raised or lowered. Sliding windows are also not unlike double hung windows in design. While a double hung window has sashes that are raised and lowered a sliding window has sashes that are movable along a track to the right or left. Similarly, sliding doors operate the same way as sliding windows.
Double hung windows, single hung windows, sliding windows and sliding doors have a variety of open positions in which they may be placed. While a fully opened position can be desirable for ventilation purposes there can be a downside to the fully opened position. One downside is security. A fully open window or door, however, can be a location for unauthorized ingress and egress from the premises. For example, a double hung window that is opened wide can be a source of danger to small children who may climb up to the window. As a result, many municipalities have enacted laws requiring window guards. Additionally, an opened window or door can provide an invitation to third parties to gain access to the building. As a result, there are a number of vent stops that are available to secure a window or door having sliding members in a partially opened position. One such stop is shown in U.S. Pat. No. 5,248,174 owned by Ashland Products. Another sash stop is shown in U.S. Pat. No. 4,923,230 owned by Ro Mai. In each of these sash stops there is a spring biased tumbler or dog that pivots from an unlocked position to a locked position as desired. These sash locks are positioned in the frame of the upper sash and when the tumbler is pivoted outwardly the position of the tumbler prevents the lower sash from being raised above a preselected position. Other prior art patents for similar products a U.S. Pat. Nos. 5,553,903 and 5,806,900 both of which are owned by Ashland.
While the vent stops of the prior art are generally satisfactory in operation there is a need for improved vent stops that are stronger and more dependable than the prior art vent stops. It is not uncommon for such prior art vent stops to be hit rather hard as one sash is moved and as a result, there have been instances where casing of the vent stop cracks open and the tumbler and/or the spring of the prior art stops become dislodged. The problems of the prior art stops is solved by the vent stop of the present invention which has superior strength due to its improved construction.